Many processes in the semiconductor and medical industries require temperature control of liquids which are corrosive, or which must be maintained at high purity levels. In the semiconductor industry, ultrahigh purity acids used in cleaning silicon wafers must be temperature-controlled during processing. De-ionized water which is saturated with ozone requires precise temperature control for proper stripping of photo-resist from wafers after plasma etching operations. In the medical industry, temperature of a patient's blood must be controlled during an operation or an analysis. In each of these examples, standard metal tube heat exchange devices, or stated more precisely, the standard metal tube heat exchanger plates, often called cold plates, in heat exchange devices, cannot be used because of the resulting metal contamination of the fluid.
Additionally, in the semiconductor industry it is desirable to be able to clean a temperature-control cooling/heating unit easily, should contamination occur. In the medical industry it is a common practice to dispose of all materials in contact with one patient to ensure no infectious diseases are transmitted to another patient. Any vessels or tubing holding blood should be replaced for the next patient. Thus, it is desirable to have the elements which contact the liquid in a heating/cooling unit be constructed either from chemically inert materials which may be easily cleaned, or from materials which can be easily replaced at low cost.
Since the heating and cooling capacities required in both industries are relatively small, thermoelectric technology can be effectively used. The present invention provides for a thermoelectric liquid heat exchange device which can precisely control the temperature of corrosive liquids or liquids of high purity without contamination. Elements which are in contact with the liquids may be replaced easily and at relatively low cost.